title: Environmental stimuli modulate the circadian rhythm of [3H-methyl]thymidine incorporation into brain DNA of male rats.
abstract: A circadian rhythm of DNA synthesis is present in most organs of adult mammals, with peak levels (acrophase) generally in the rest period. We have recently reported that in the rat brain the acrophase of the rhythm of thymidine incorporation into DNA occurs on the contrary during the active period. To determine whether the brain waking activity was exerting a modulatory action we measured the circadian rhythm of incorporation in the brain and kidney of young adult male rats housed in conditions of sensory and social enrichment or impoverishment for four days. Biochemical and autoradiographic data show that the brain rhythm persists in the enriched condition, but is abolished in the impoverished condition. On the other hand, the rhythm of incorporation in the kidney is maintained in both conditions. These results suggest that the permanence of the brain oscillation is selectively dependent on the complexity of the sensory and social stimulation.
authors.affiliation: Istituto di Biologia Cellulare, Università di Perugia, Italy.
authors.forename: G G
authors.initials: GG
authors.lastname: Zucconi
authors.forename: M C
authors.initials: MC
authors.lastname: Crognale
authors.forename: M A
authors.initials: MA
authors.lastname: Bassetti
authors.forename: A
authors.initials: A
authors.lastname: Giuditta
mesh_terms: D000818:Animals; D001143:Arousal / Q000502:physiology*; D001345:Autoradiography; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D002940:Circadian Rhythm / Q000502:physiology*; D004261:DNA Replication / Q000502:physiology*; D007668:Kidney / Q000502:physiology; D008297:Male; D009473:Neuronal Plasticity / Q000502:physiology*; D009474:Neurons / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D012931:Social Environment; D013936:Thymidine / Q000031:analogs & derivatives* / Q000493:pharmacokinetics
chemical_list: C012439:methylthymidine; D013936:Thymidine